Origen

Before wing came into English from Old Norse vængr, the term used was feathers, an Old English word from a Germanic root. In a theatre the wings are where actors wait for their cue to come on stage: someone waiting in the wings is ready to do something at the appropriate time. To wing it, or do something without preparation, is originally theatrical slang, which meant ‘to play a role without properly knowing the text’, either by relying on a prompter in the wings or by studying the part in the wings between scenes. It was used in this sense from the late 19th century, but did not acquire its more general meaning of ‘improvise’ until the 1950s. On a wing and a prayer, ‘with only the slightest chance of success’, is from the title of a 1943 song by the American songwriter Harold Adamson, ‘Comin’ in on a Wing and a Pray'r’. He took it from a comment made by a wartime pilot speaking to ground control just before he made an emergency landing in his damaged plane.

under one's wing

On the evidence it appears as though Anne Kelly, Jennifer's mother, took Jennifer's two boys under her wing and cared for them until Jennifer was finally able to resume her motherly duties on a full-time basis.

Krystal and I had sort of taken him under our wing and protected him from the assholes who disliked him.

There were times when you could look out your own bedroom window and envy the other kids outside who got to play whenever they wanted, while your mom kept you in, under her wing, to protect you.